trubleshooting a Taco

Treat91

Hello. first and foremost, im soryy for my ignorance on this, that is why im here.
I moved into a condo that has (Taco ZVC 404)heating system with floor base radiators. I have come to learn of zones i have a zone or zone's that iant working. my bottom floor and 2nd floor work but the upstairs 3rd floor isnt responding. the thermostats are also taco. I looked at my Taco system and noticed these lights did a little homework and still do not understand.

STEVEusaPA

Shut the main switch off, replace the batteries in the thermostats. Turn on switch, wait a few minutes. If that doesn't work you'll have to call a professional to diagnose the problem with a DMM

Each zone has 2 lights. One to tell you there is a call for heat, and the other to tell you the zone valve opened. From your pic only zone 3 is calling for heat. So it could be the thermostats, the zone valves (less likely) or the control.
The bottom light is just telling you the control has power.

EdTheHeaterMan

It is apparent that you have zone valves from the control you pictured. It also appears that the valve has power to the actuator (the head or motor), because the green light is lit. Now if you have 3 or 4 wire zone valve the red light means that valve opened. (if you have a 2 wire zone valve then the red light does not mean anything). Assuming 3 or 4 wire zone valves, the red light means the valve opened, now the pump can circulate water thru the zone. If the water is not circulating... there is air in the loop. the circulating pump can not pump air... only water. You will need to get the air out of the loop. If you are not sure how to do that. look on YouTube for videos on "Purging air from Baseboard Radiators"

Note... if you have 2 wire zone valves than you may not have air in the radiators. Look at the wires that go to motorized valves on the 3/4" pipes The wires come from the bottom connectors that have 4 screw post to connect wires.



This illustration shows 2, 3 and 4 wire valve connections

if you have the 2 wire valves your wires will look like the ZONE 1 example. If you have wiring like ZONE 2 or 3, then you most likely have air in the loop.

IF YOU HAVE MORE QUESTIONS: take pictures of the pipes on the boiler system and close-ups of the zone valves including the wires

rick in Alaska

Also, if the boiler pressure is not high enough, you will not get heat upstairs. Depending on how tall your floor levels are, you would need about 18psi on the boiler gauge. Take a picture of the piping around the boiler and a picture of the pressure gauge and we might be able to give you a better answer. Assuming the gauge works, of course
Also, assuming zone three is your upstairs zone, the thermostat is working ok.
Rick

HVACNUT

I agree with @rick in Alaska .
It might not be electrical at all. Can you see the pressure gauge on the boiler? What does it read in PSI?
Can you hear or feel if the circulator is running?
I H8 truble.

Treat91

pic 1

Treat91

this is zone three. sone before has left marks on them. im assuming its up stairs since there is no heat. lights are still on. the only pressure guage i see reads above 50psi.

Alan (California Radiant) Forbes

Everything looks OK, but the pressure over 50 psi is not good since it should be between 15-25 psi. At 30 psi, your relief valve there at your boiler should open and dump water out. So, either your gauge is wrong or your relief valve is stuck closed.

Turn all your thermostats on and after about a minute, take a picture of the lights on your Taco ZVC404.

What part of the country are you in?

HomerJSmith

Are you sure you are reading the pressure dial on the tridicator and not the temp dial? Tridicators get plugged with debris and fail. Put a hose bibb gauge on any hose bibb on the sys and look at the pressure on the hose bibb gauge to confirm that the reading is the same as the tridicator. If not replace the tridicator.

The picture of all the Sentry zone valve shows open so water should be flowing thru it. Feel the output of the zone valve for the floor that's not heating, the one in the picture that is closed #4?, open that one manually by pushing in and rotating the green knob until the line on the knob is vertical and then feel the output of the zone valve of a floor that is working. Do the temperatures feel the same? If not, then the water isn't flowing thru it. If it get hot and the 3rd flr get hot the zone valve is bad or not charging.

Pull the left terminal with the red and white wire off all the zone valves except the floor that isn't heating. All the disconnected zone valves will close. Does the pipe on the output of the zone valve for the one still connected get as hot as the ones that are disconnected and you get heat on the 3rd flr? The boiler should be firing and the pump should be running.

If you don't get heat then I would say that a valve in that circuit is closed, you have an air lock on the third flr baseboard or your expansion tank, if a Fill-Trol 110, it is under inflated or a separate Pressure Fill Valve is malfunctioning and the Extrol expansion tank is under inflated. For 3 stories above the boiler you need at least 15 psi with a cold sys. It takes 1psi for every 28" above the boiler to the top of the baseboard on the 3rd flr+ 5psi.

Connect all the zone valve and keep them in the open position and do the hand feel test again.

I would first measure the boiler pressure with a hose bibb gauge to see if the boiler tridicator is accurate.

https://www.supplyhouse.com/Winters-Instruments-PETM213-2-1-2-PET-Economy-Maximum-Pointer-Water-Test-Pressure-Gauge-0-160-PSI

HomerJSmith

There is a green led between the two connectors to the sentry zone valve. When charging it is blinking, when charged it is green. If it is out and the thermostat is calling for heat you may not be getting power to the zone valve.
Check the electrical connection in the Taco ZVC404. Check the wiring to the thermostat and the thermostat. You can determine if the thermostat and wiring is good, just jump the TT connection for that thermostat in the Taco ZVC404 and see if the zone valve opens.

joemat

Hi Treat91
hopefully you've troubleshooted your system, and you have heat. however, if you're still having trouble you can contact Taco Tech support at 401-942-8000, and ask for tech support. We're proud to have a live person, and not a robot to answer your call and direct you to tech support.
I read through this tread and found so many variables that could absolutely resolve your issue which is why I asked if any of them did? I'm curious what the problem was? taking zone valve head off and using a clamp to push down on the valve body will help bring hot water to 3rd floor when another floor has a demand. of course the thermostat on third floor won't regulate temperature as we circumvent to provide heat. that will also tell us if the zonevalve head is the culprit. hopefully this was helpful